Since the second half of the '90s, investment incentives channeled through the Law 488 have represented the main policy instrument for reducing territorial disparities in Italy. From 1996 to 2003, the total amount of funds distributed to industrial firms has accounted for 16 billions of Euro involving 27,846 financed projects mainly in the southern regions. The Law 488 allows firms willing to invest in lagged areas to receive a public subsidy that covers a fraction of the investment outlays. The incentives are assigned through competitive auctions according to pre-determined specific criteria, such as the proportion of own funds invested in the project; the number of jobs involved and the proportion of assistance sought. This paper aims at evaluating the impact of Law 488 subsidies on firms' investment. We employ a linked dataset that matches for all the firms that have applied for the grants - both subsidized firms and firms with rejected applications - the features of the Law 488 intervention with financial account data that covers both pre-intervention and post-intervention periods. The focus is to evaluate whether the Law 488 made it possible investments that otherwise would not have been done. In doing so, we compare the investment performance of subsidized firms with that of the firms that applied for the grants but were not financed. We analyze the extent to which investments have been triggered by intertemporal substitution (firms could have anticipated investment projects originally planned for the post-intervention period to take advantage of the incentives). Moreover, we study the role of cross-sectional substitution (subsidized firms could have taken some of the investment opportunities that non-subsidized firms would have got in absence of the incentives). We find that financed firms have substantially increased their investments when compared with the pool of rejected application firms. We also find evidence of intertemporal substitution: financed firms slow down significantly their investment activity in the years following the program. Finally, the impact of the L488 is more pronounced when the size of the market where the firms compete is small or when the firms are close as for their industrial distance, so to suggest that financed firms displace their non-financed competitors.